Morphology Data of Acanthurus nigricauda
Identification keys
Abnormalities
Main Ref. Randall, J.E., G.R. Allen and R.C. Steene, 1990
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors
Remarks

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral short and / or deep
Cross section compressed
Dorsal head profile clearly convex
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales ctenoid scales
Diagnosis

Color in life dark brown without lines on body or spots on head (one phase is purplish grey); horizontal black band behind upper gill opening absent on juveniles <6 cm SL; elongate purple band may be present anterior to dorsal origin; caudal fin brown; outer third of pectoral fin pale. Species with gizzard-like stomach.

Description: Characterized further by having white bar at base of caudal fin; length of caudal spine 2.8-4.5 in head length; greatest depth of body 2.0-2.2 in SL (Ref. 90102).

Ease of Identification

Meristic characteristics of Acanthurus nigricauda

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Barbels 0
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 20 - 21
Vertebrae
preanal
total

Fins

Dorsal fin(s)

Attributes extending over most of the back length
Fins number 1
Finlets No. Dorsal   0 - 0
Ventral  0 - 0
Spines total 9 - 9
Soft-rays total 25 - 28
Adipose fin absent

Caudal fin

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 3 - 3
Soft-rays total 23 - 26

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   17 - 17
Pelvics Attributes  more or less normal
Position    thoracic  behind origin of D1
Spines     1
Soft-rays   5 - 5
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